WIXTEECxREEX. 333 



salicylic acid, 2 parts of anhydrous wood spirit and 1 part of 

 sulphuric acid. This artificial methyl salicylate is not considered 

 by some to possess a fragrance equally fine to that of the natural 

 product, but that is a matter of opinion, or it may be due to the 

 fact that salicylic acid of commerce, which is used in its manufac- 

 ture, is not pure, but contains from 0"o to 1 per cent, of cresotic 

 acid (being made from phenol).* The sp. gr. of sijntlietiG 

 wintergreen oil, when Cjuite pure, prepared from saKcylic acid 

 absolutely free from cresotic acid, is found by Messrs. Schimmel to 

 be 1-1870 at 15^ C, and its boihng point 219^^ to 221° C. This 

 sp. gr. pertains to an oil entirely free from water. The oil of 

 commerce, which is distilled with water-steam, generally contains, 

 as is well known, small quantities of water, which cause some 

 variations in the third decimal place. 



For the detection of free salicylic acid in synthetic methyl 

 salicylate, Schneegans and Gerock observe as follows : — The violet 

 colour resulting from the mixture of 10 c. c. of a 0*2 per cent, 

 solution of salicylic aldehyde with 2 c. c. of a very dilute solution 

 of perchloride of iron, may be removed by shaking it with 5 c. c. 

 chloroform or ether. But if only 0*0002 gram, of salicylic acid 

 be added, the violet colour remains persistent. A similar reaction 

 occurs with the methyl ester of salicylic acid, and it may be used 

 to detect as little as 1 in 500 of free acid in artificial oil of 

 wintergreen.-i* 



The Wintergreen oil of commerce is largely adulterated with 

 Methyl henzoate,^ and if the odour of the compound is not sufiicient 

 to indicate the presence of it, it may be suspected and tested for 

 by reason of low sp. gr ; that of methyl benzoate being 1"095 at 

 15° C. 



Pure oil of Gcudtheria 2^^^ocumhcns is said to rotate slightly to 

 the left (about — 2° in a 200 m. m. tube), whilst pure oil of Bdula 

 lent a and pure methyl salicylate are both optically inactive. 



American pharmaceutical journals have recently attempted to 

 establish a test to distinguish between natural and synthetical 



* The assay of artificial salicj'lic acid is described by Ewell and Prescott, 

 Pharui. Journ. [3 J, xix., p. 328. 



t Pharm. Journ. [3], xxii., p. C09. 



X Series i,, p. 238 ; the sp. gr. should there have been stated to be r095 at 

 15° C. 



